This invention relates to an electric, remotely controlled, lock operating mechanism for a vehicle door, including alternate manual operating means.
There are two basic types of door lock operating mechanisms, one of which includes a solenoid drive and the other of which includes an electric motor drive. The former is unduly large, costly and noisy, whereby the latter has been more widely adopted in recent years.
In the latter type of mechanism, installation in a limited space (within a door frame) is enabled by using a small, compact motor coupled to a high ratio reduction gear mechanism. However, if alternate manual operation must be provided, as for safety consideration with vechile door locks, the operator must exert considerable effort since he must "spin up" both the reduction gears and the motor. To avoid this drawback a large motor and low ratio reduction gear mechanism can be used, but then the limited installation space presents a problem.
To obviate these drawbacks, according to Japanese patent publication No. 50-16048 a centrifugal clutch is employed which automatically disengages the drive train when the motor is deenergized, whereby manual operation may be achieved with reduced effort. The force required is still relatively large, however, since the manual control lever is connected to and must drive the high ratio reduction gear mechanism. Further, if the door is mistakenly locked by the manual control lever when the door is open, the lock is automatically released when the door is closed. During such release, however, the reduction gear mechanism is rotated at a relatively high speed, which often causes damage to or failure of the gear mechanism.
To obviate these drawbacks, according to Japanese patent publication No. 48-40275 as shown in FIG. 11, a manual door lock knob 100 is provided with a pawl 101 movable between an upper stop 102a and a lower stop 102b of a slide member 102. The distance between the stops is substantially equal to the stroke of the knob 100. The slide member 102 is guided in a groove 103 and is connected to the output shaft 104 of a reduction geared motor, whereby the member 102 slides on the groove 103 in response to the rotation of the motor to automatically lock or unlock the door. With this structure, the movement of the knob during manual operation is not transmitted to the reduction gear or motor as long as the slide member 102 is maintained at a neutral position between its door lock and door unlock positions. However, it is necessary to provide a mechanism for stopping the rotation of the motor when the slide member 102 is at its neutral position, and such mechanism is mechanically complicated and costly.